Various techniques such as a technique using reference light and a stereo distance measuring technique using two or more cameras have been suggested as imaging techniques for obtaining information about the distance to an object in the depth direction as two-dimensional array information. Particularly, in recent years, there has been an increasing demand for relatively inexpensive products as novel consumer input devices.
In view of this, an imaging device that has a multi-view structure and includes an imaging lens has been suggested as a structure for obtaining a large number of parallaxes from multiple viewpoints, and restraining a decrease in resolution. This imaging device has an imaging lens, for example, and has a multiple optical system as an image re-forming optical system located between the imaging lens and an imaging element. As the multiple optical system, a microlens array or the like having a large number of minute lenses formed on a flat surface is used. Pixels for obtaining the images of the microlenses are provided at corresponding locations below the respective microlenses. An image formed at the imaging lens is re-formed on the imaging element through the image re-forming microlenses, and the re-formed single-view image is an image having a shift in viewpoint. The shift is equivalent to the parallaxes existing because of the locations of the microlenses.
By performing image processing on parallax images obtained through the large number of microlenses, the distance to the object can be estimated by using the principle of triangulation. Further, by performing image processing to combine such parallax images, the parallax images can be re-formed as a two-dimensional image.
In the above-described imaging device having a multi-view structure, however, the focal plane of the imaging lens is shifted forward (toward the object) to a position before the imaging element when the object is located at an infinite distance. Therefore, when the same imaging lens as above is used, camera height is increased.